The present invention relates to a dispensing assembly having coded attachment of an accessory to a dispensing device, particularly attachment of a mixer to a multiple component cartridge.
There exists a great number of mixers and cartridges having means for attaching the mixer to the cartridge. For example, U.S. Pat. Nos. 4,767,026 and 4,538,920 disclose a mixer that has two bayonet locking lugs inserted into corresponding prongs on the cartridge by rotation. On one hand, the rotary locking movement of the complete mixer will cause contamination of one chemical component against the other chemical component at the interface between the cartridge and the mixer, in that these components will be transported from one outlet to the other outlet, from one inlet to the other inlet, causing an undesired reaction between these chemical components at the interface between cartridge and mixer or closure means, and eventually carrying such a reaction back into the cartridge outlets, thus causing plugging of the outlets. On the other hand there exist situations where it is necessary to connect and attach the mixer or accessory to a multiple component cartridge or dispensing device in a predetermined position, such as when cartridge outlets or mixer inlets are of a different size for different relative mixing ratios or when mixers or accessories are refitted for reuse.
There exists a need to connect and attach a mixer or accessory to a multiple component cartridge or dispensing device in a predetermined orientation, such as when cartridge outlets or mixer inlets are of a different size for different relative mixing ratios or when special high ratio mixers are used for greater mixing efficiency and when mixers or accessories are refitted for reuse. In the latter case of reuse, it is necessary to avoid any possibility of cross contamination of one chemical component against another during refitting. Such cross contamination of reactive chemical systems can cause plugging at the cartridge outlets and cause a reaction back into and within the cartridge.
U.S. Pat. No. 5,228,599 discloses a multiple dispensing cartridge having a mixer attached thereto with the aid of a coupling nut having an internal thread, wherein each storage cylinder ends in a dispensing opening which forms a side by side outlet, whereas the inlet of the mixer is not defined. The mixer is put on the cartridge and secured by a coupling nut via an external thread at the cartridge.
Another cross contamination situation can occur when a clean mixer or accessory inlet area or closure plugs are able to make any form of incorrect alignment contact, such as by angular tipping, with the chemical components at the cartridge outlet area during the process of initial placing of the mixer or closure plugs against the cartridge in preparation for attachment. In that case, when fitting the same mixer or closure plugs in the correct position, it is possible to chemically contaminate the outlets of the cartridge. Again, this can cause plugging and a reaction back into and within the cartridge.
Additionally, it is commonly found in bayonet attachment means of the prior art that the bayonet prongs of the cartridge are relatively small and therefore of limited structural rigidity and strength. This allows the possibility of distortion and is of greater significance due to the trend towards smaller mixer diameters and therefore high backpressures, the result being leakage at the mixer to cartridge sealing interface during dispensing. Further, prior bayonet attachment means typically do not provide sufficient strength for the connection of large cartridges with large outlets.
In accordance with an embodiment of the present invention, there is disclosed a dispensing device that includes a cartridge, a mixer, a threaded coupling ring, and complementary coding elements formed on the cartridge and mixer. The cartridge includes a plurality of chambers each having an outlet, and a threaded flange. The mixer is comprised of a housing with a plurality of inlets corresponding in number to the outlets. Each inlet is configured to engage a respective one of the outlets and a mixer element disposed in the housing. The coding elements permit the inlets of the mixer to be aligned and connected to the respective outlets of the cartridge in only one orientation.
In accordance with another embodiment of the invention, there is disclosed a mixer for a cartridge having a plurality of chambers, each with an outlet. The mixer includes a housing, a mixer element disposed in the housing, a plurality of inlets for engagement with the outlets of the cartridge, a coding element and a threaded coupling ring. The plurality of inlets are mounted at the inlet section of the housing. The coding element permits the inlets of the housing to be aligned and connected to the outlets of the cartridge in only one direction. The threaded coupling ring detachably connects the mixer to a corresponding thread on the multichamber cartridge, and has locked and unlocked positions.
In accordance with still another embodiment of the invention, there is disclosed a cartridge for a mixer having a plurality of inlets. The cartridge includes a plurality of chambers each having an outlet formed at a threaded flange for engagement with the inlets of the mixer, the threaded flange receiving a threaded coupling ring, and a coding element that permits the outlets of the chambers to be aligned and connected to the respective inlets of the mixer in only one orientation.
According to one feature of the invention, the mixer inlets have differently sized diameters which match corresponding cartridge outlets.
According to another feature of the invention, the coding element includes a marking in the form of an incision at the circumference of the inlet section.
According to another feature of the invention, the coding element includes protrusions on the inlet face of the mixer.
According to another feature of the invention, the coding element includes tongues at the housing of the mixer having different widths which mate with corresponding slits having different widths.
Other aspects, features and advantages of the invention will be apparent from the following description.